This invention relates to glue applicators of the type that apply a film of glue to sheet material, such as to boxes or cartons, and more particularly to a glue pot for supplying a continuous stream of hot liquid glue to the applicator rolls of a glue applicator.
When glue is applied to sheet material, it is highly desirable to have the glue at a desired temperature and viscosity so that the glue can be spread easily and applied in an even coat to the sheet material. As the temperature of the glue is reduced, it becomes more viscous and eventually becomes hardened and unusable. When the operation of a glue applicator is terminated and the supply of glue is cut off, it is highly desirable to clean the glue applicator immediately after its operation has been terminated so as to remove the glue from the glue applicator. Otherwise, the temperature of the residual glue that remains in the glue applicator will drop, causing the glue to solidify and clog the working components of the equipment. Similarly, when a glue applicator is to be started up at the beginning of a work cycle, the glue must be heated in order that it change from a solid state to a liquid state so that the glue can be applied to the sheet material.
In the past, heated glue pots have been used to supply hot liquid glue to the applicator rolls of a glue applicator. The prior art glue pots include a double wall chamber that includes a main glue reservoir surrounded by a hot water reservoir. The glue is drawn from the lower portion of the glue reservoir and pumped through an insulated conduit to the applicator rolls of a glue applicator, and the excess glue from the glue applicator is drained back to the glue reservoir. Some of the problems experienced with the prior art glue pots are that the structure is expensive in that it requires a double wall container, the body of glue in the glue reservoir tends to form a film on the top of the glue, and a long time is required to heat the glue in the glue reservoir to the proper temperature and viscosity when the equipment is to be started at the beginning of a work cycle. Also, when additional glue is to be added to the glue reservoir, the additional glue, which usually is in solid form, tends to sink to the bottom of the glue reservoir and clog the inlet of the pump which draws the glue from the glue reservoir and delivers the glue to the glue applicator equipment.